The goal of this program is to understand the regulation and disregulation of the immune system in autoimmunity. The program involves collaborative interactions between members of three departments, and is organized into four projects supported by three core facilities. Expertise in the field of immunology, molecular biology, and biochemistry will focus on the events that initiate and sustain autoimmune responses, and the regulatory processes, which contain autoimmunity. We will address the following questions. What are the requirements to initiate autoimmune responses? Are autoimmune responses regulated, and if so, by what mechanisms? Does immune regulation contain autoimmune responses under normal circumstances? Finally, do sustained autoimmune responses remain chronic because they diversify from a single initiating response to responses to other autoantigens from the same tissue? These questions will be addressed by collaborative interactions between the Principal Investigators of these projects, which are as follows: (1) R.A. Flavell -Dr. Flavell will address the role of IL-10 in autoimmune disease. First, he will develop a novel model system to visualize IL-10 production in vitro and in vivo. Using a GFP knock-in strategy, IL-10 producing cells will be detectable through GFP expression. This will be used to visualize IL-10 production during EAE and IBD and can be used to monitor the effects on IL-10 of a number of interventional strategies, including Dr. Janeway's "therapeutic vaccination" using skin patch. He will also address whether IL-10 acts on T cells or antigen presenting cells in mediating its effects on EAE and IBD using mice transgenic for receptors that block IL-10 action. He has previously used this approach successfully for the other regulatory cytokine TGF-beta. This approach therefore appears promising. (2) C.A. Janeway Jr. -This project will examine the ability to generate suppressor or regulatory T cells in mice that are transgenic for the TCR of the MBP specific clone on a B10.PL background. They have recently observed that they can generate such cells in both induced and spontaneous disease. They will determine if they can observe the same phenotype in normal B10.PI mice, and mice reactive to other autoantigens. (3) M.J. Shlomchik -Transgenic mouse models will be used to study the regulation of B cells expressing a disease- related autoantibody, rheumatoid factor (RF), in normal and autoimmune mice. These B cells are activated spontaneously in autoimmune-prone mice, yet remain quiescent in normal mice. This system will be used to: 1 ) determine the factors -environmental and genetic -that are required for the onset and early propagation of disease; 2) define the cascade of events that leads from an initial nidus of proliferating autoreactive B cells to chronic, ongoing disease; and 3) determine the identities, at the phenotypic and molecular level, of the unique B lineage cells that have escaped peripheral tolerance. (4) M.J. Mamula -Overall, this proposal will examine B cell- T cell interactions in systemic autoimmune disease. The work will make use of autoantibody transgenic mice to determine their role in the maintenance of immune tolerance in normal strains of animals versus the induction of autoimmunity and pathology in autoimmune prone mice. Additional studies will examine how the levels and exposure to self antigens in vivo control the induction and perpetuation of B and T cell autoimmunity. These four projects will be supported by an Administrative Core (Core A) to coordinate the project as a whole, a genetically modified mouse core (Core B) to provide gene targeted and transgenic rodents essential to most of these studies, and a Cell Separation Core (Core C) to allow us to isolate cells and to analyze cells in all of these projects. The program is coordinated by frequent meetings of the program faculty and research workers bringing together these diverse approaches to address a common goal.